TABLE 1.
Sociodemographic, pregnancy, and delivery characteristics of mothers with very low milk production, moderate milk production, and controls1
| Milk production group2 | ||||
|---|---|---|---|---|
| VL (n = 23) | MOD (n = 20) | Control (n = 18) | P value3 | |
| 24-H milk production, mL/d | 162 ± 87c | 520 ± 172b | 822 ± 172a,3 | <0.001 |
| Maternal age, y | 31 ± 6.3 | 32 ± 3.4 | 31 ± 4.7 | 0.58 |
| Ethnicity, white | 91 | 95 | N/A | 1.00 |
| College graduate | 65 | 85 | 89 | 0.18 |
| Parity, primiparous | 57 | 45 | 33 | 0.33 |
| Gestational diabetes | 22 | 5 | 6 | 0.21 |
| Vaginal delivery | 52 | 80 | 78 | 0.09 |
| Gestational age at birth, wk | 39 ± 0.9 | 39 ± 1.2 | 40 ± 1.1 | 0.11 |
| Infant sex, male | 43 | 45 | 39 | 0.93 |
| Days postpartum at baseline | 31 ± 18 | 33 ± 16 | N/A | 0.72 |
| Days postpartum at milk sample | 41 ± 18 | 43 ± 23 | 52 ± 12 | 0.14 |
| Baseline time point of milk sample4 | 65 | 70 | N/A | 0.74 |
| Breast emptying frequency,5 times/d | 18 ± 6a,b | 20 ± 8a | 14 ± 4b | 0.048 |
Values are mean ± SD or percentages. Group differences for normally distributed data were analyzed by 1-factor ANOVA with Bonferroni adjustment for repeated measures. Group means in a row with different superscript letters were significantly different (P < 0.05). Dichotomous variable differences were assessed by Pearson chi-square test. MOD, moderate milk production group; N/A, not available; VL, very low milk production group.
Milk production groups were defined as VL (<300 mL/d), MOD (≥300 mL/d), and control (externally recruited controls who were exclusively breastfeeding infants with healthy weight gain).
For the control group, n = 12 for milk production measured by test-weigh.
We used samples from the time point with maximal milk output from the low milk supply study (baseline or 4 wk). Controls were only assessed at 1 time point.
Breast emptying frequency was based on each breast counted separately.